The present invention relates to mounts and fasteners. More specifically, the present invention relates to fasteners for affixing thermal insulation blankets to a substrate, such as the engine nacelles of an aircraft.
It is common to secure an “attachment member” such as a fastener or the like, onto a supporting surface, also referred to as a substrate. For example, it is known to mount threaded fasteners or the like onto a substrate so as to be able to attach additional components to the substrate's surface. Adhesive bonded attachments are well known for connecting a component to a threaded stud or bolt so as to mount components to a substrate. These adhesive attachment members typically include a base providing a bonding surface which is adapted to receive a curable bonding agent. The base is then pressed against the substrate surface so as to allow the bonding agent to cure.
Attachment members including a base and male or female threaded fastener have been used to support and affix thermal insulation blankets to a substrate wherein the insulation blanket is provided to act as a heat-shield to protect surrounding structures and components. As but one example, such thermal insulation blankets have been mounted on the inboard side of aircraft engine nacelles. Typically, a thermal insulation blanket is made of a refractory cloth material which includes multiple grommets forming mounting holes for affixing the blanket to the substrate. A plurality of adhesive bonded attachment members are affixed to the nacelle substrate at various positions with the attachment members' male or female threaded elements projecting through the insulation blanket's mounting holes. Separate cooperative threaded elements, such as nuts or bolts, are then secured to the attachment member's threaded elements for retaining the insulation blanket in place.
As a result of the high heat environment, specialized fasteners have been developed. For example, U.S. Pat. No. 7,584,582, which is incorporated by reference herein, discloses an adhesive bonded attachment assembly for use in affixing insulation blankets to a substrate. The attachment assembly includes an attachment member including a base for adhesively affixing to a substrate as well as a threaded element for projecting through an insulation blanket's mounting hole. In addition, the assembly includes a cap having a radially enlarged cap member and a second threaded element for affixing to the attachment member. The cap member has a size so as to overlie and engage the insulation blanket so as to keep it in place. Providing additional thermal protection, the cap member has an inboard piece and an outboard piece forming an internal chamber. The cap's inboard piece and outboard piece are typically made of metal and an insulation material is positioned within the cap's central chamber. Unfortunately, the fastener assembly described in U.S. Pat. No. 7,584,582 suffers from several drawbacks. First, because the fastener assembly is primarily made of metal, the assembly is undesirably heavy. In addition, the cap fastener is made of multiple components which must be assembled together thereby introducing undesirable complexity.
All-metal fasteners provide extremely high strength to a fastener element. However, adhesives and potting materials typically do not bond well to an all-metal material, such as titanium, as well as to a composite or plastic material. Further, metal fasteners are typically heavy and expensive. Conversely, plastic fasteners provide low weight, but lesser strength values than all-metal fasteners.
Therefore, there is a significant need for an improved attachment assembly for affixing insulation blankets to a substrate.
It would be desirable to provide the fastener assembly with a decrease in weight, reduced manufacturing costs, and improved thermal protection.